Acrocalymma Alcorn & J.A.G. Irwin, Trans. Br. Mycol. Soc. 88(2): 163 (1987)
Dothideomycetes, Pleosporomycetidae, Pleosporales, Acrocalymmaceae
Saprobic on terrestrial host plant and freshwater water habit. Sexual morph: Ascomata initially immersed, later becoming erumpent, globose, unilocular, covered with light pale grey hyphae, opening by a centrally located ostiole, with a long break. Ostiole cylindrical, filled with hyaline periphyses. Peridium composed of thick-walled, brown cells of textura angularis. Hymenium composed of numerous, hyaline, filliform, septate, anastomosed pseudoparaphyses and asci. Asci bitunicate, 8-spored, cylindrical, short pedicellate. Ascospores biseriate, initially hyaline, ultimately becoming brown or pale reddish brown, narrowly fusiform, straight or slightly curved, 1–3-septate, constricted at septa, thick-walled, guttulate, enclosed by 1–2 μm wide, hyaline sheath. Asexual morph: Conidiomata dark brown to black, solitary to gregarious or confluent, immersed to semi-immersed, stromatic, pycnidial, globose to subglobose, pyriform, unilocular or multi-locular, ostiolate. Ostiole circular, cylindrical, straight or curved, centrally or laterally located. Conidiomatal wall composed of brown to paler, thick-walled cells of textura angularis to textura globosa or textura prismatica. Conidiophores reduced to conidiogenous cells. Conidiogenous cells hyaline, enteroblastic, phialidic, ampulliform to subcylindrical or lageniform, smooth-walled. Conidia hyaline, cylindrical to fusiform, aseptate or 1–3-septate, bearing helmetshaped, mucoid appendage at each end.
Type species: Acrocalymma medicaginis Alcorn & J.A.G. Irwin, Trans. Br. Mycol. Soc. 88(2): 163 (1987)
Notes: Acrocalymma was introduced by Alcorn and Irwin (1987) for a single species, A. medicaginis, which was associated with a root and crown rot disease of Medicago sativa (Fabaceae). Acrocalymma is characterized by globose conidiomata with a long pycnidial beak, and hyaline, or becoming pale brown with age, cylindrical to fusiform, aseptate, or 1–3-septate conidia, bearing an appendage at one or both ends. Za.
Distribution: Australia, India, Spain, Thailand, USA (Alcorn and Irwin 1987; Nag Raj 1993; Trakunyingcharoen et al. 2014, this study).
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.